I have numerous docker containers running all without issues, except for one which I had to do a workaround to get working.
It appears all of my docker containers run the apps inside them under a root instance.
The one container I'm having a problem with runs it's application (a node instance) as a non-root user. The problem is it doesn't have any network access. I tried to troubleshoot this by attaching to the shell session within the container and tried an nslookup which failed. Tried to run a ping but ping required root access (which was odd but whatever). I then closed the session and reattached to the shell as root and had no issues with nslookup or ping.
I installed docker on an ubuntu VM, pulled the same image and copied the folder with all of the config files over to it, mapped the volumes, etc and ran the docker container and it had no problems at all running as the image was written.
Back on OMV, I deleted the image, and using portainer I copied the dockerfile information but left out the following lines:
RUN chown 1000:1000 -R /app
USER node
Ran the image, pointed the volumes the same as before, and it worked just fine.
Do the same, but re-add those lines, and no network connectivity.
Is there any specific reason why the docker install on OMV will deny network rights within a container when the program running in the container is run by a user other than root? I'm pretty sure I tried running the container as a different user and had the same issues.